The present invention relates to olefin thermoplastic elastomer compositions for skin members and laminates thereof. More particularly, the invention relates to olefin thermoplastic elastomer compositions for skin members having excellent slide abrasion resistance and extrusion moldability, and also relates to laminates thereof.
Olefin thermoplastic elastomers are lightweight, can be easily recycled and generate no noxious gas when they are incinerated, so that they have been intensively used for various materials such as automobile parts, industrial mechanical parts, electronic or electric parts and building materials from the viewpoints of conservation of energy, conservation of resources, and recently, global environmental protection.
An example of the automobile part is a glass run channel. The glass run channel is a guide member provided between a window glass and a window frame, and is required to not only facilitate opening and closing operations of the window glass but also enable the window glass to be shut tightly (fluid-tightly) on the window frame.
Conventional glass run channels comprise a substrate made of a soft synthetic resin (e.g., soft vinyl chloride resin), an ethylene/propylene/diene copolymer rubber or the like and a nylon film for sliding a window glass, said nylon film being laminated to the substrate with an adhesive. In order to decrease the contact area with the window glass, embossing is performed before or after lamination of the nylon film.
Since the process for producing such conventional glass run channels includes a laminating step using an adhesive, the resulting glass run channels have a drawback in that separation between the substrate and the skin layer is liable to occur, and the process is complicated because of many steps.
Under such circumstances, the present inventors have paid attention to the olefin thermoplastic elastomers and tried to solve the problems of the glass run channels. In the use of the olefin thermoplastic elastomer for a single-layer glass run channel, however, the sliding properties for the window glass become bad to cause violent abrasion. Besides, the amount of a die residue brought about in the extrusion molding process is larger than the case of using ordinary resins, and the die residue adheres to the molded article, resulting in bad appearance.
In Japanese Patent Laid-Open Publication No. 176408/1997, it is described that addition of a fatty acid amide to an olefin thermoplastic elastomer enhances sliding properties and abrasion resistance. Even in the use of the thus obtained olefin thermoplastic elastomer composition, however, a problem of occurrence of a die residue in the extrusion molding still remains.
The present invention is intended to solve such problems associated with the prior art as described above, and it is an object of the invention to provide a resin composition for a skin member, which comprises an olefin thermoplastic elastomer and other specific components and which is capable of providing a laminate when it is used for a skin member, said laminate exhibiting good sliding properties for a window glass and excellent abrasion resistance and having only a slight amount of a die residue brought about in the extrusion molding. It is another object of the invention to provide a laminate using the resin composition.
The first resin composition for a skin member according to the present invention comprises a completely or partially crosslinked olefin thermoplastic elastomer (A) in an amount of 100 parts by weight, an organopolysiloxane (B) having a viscosity (JIS K2283, 25xc2x0 C.) of not less than 1xc3x97106 cSt; preferably 1xc3x97106 to 1xc3x97108 cSt in an amount of 2 to 20 parts by weight and an organopolysiloxane (C) having a viscosity (JIS K2283, 25xc2x0 C.) of not less than 10 cSt and less than 1xc3x97106 cSt in an amount of 0.5 to 5 parts by weight. In this composition, a polyolefin resin (D) in an amount of 5 to 150 parts by weight and/or a fluoropolymer (E) in an amount of 0.5 to 10 parts by weight may be contained.
The second resin composition for a skin member according to the present invention comprises a completely or partially crosslinked olefin thermoplastic elastomer (A) in an amount of 100 parts by weight and a fluoropolymer (E) in an amount of 0.5 to 10 parts by weight. In this composition, a polyolefin resin (D) may be contained in an amount of 5 to 150 parts by weight.
The fluoropolymer (E) is preferably a hot-melt fluoropolymer, particularly preferably a vinylidene fluoride/hexafluoropropylene copolymer or a tetrafluoroethylene/hexafluoropropylene/vinylidene fluoride copolymer.
The laminate according to the present invention is a laminate formed by laminating a skin member comprising the first or the second resin composition to a core comprising a thermoplastic elastomer.
The above-mentioned compositions are excellent in sliding properties for glasses and abrasion resistance and bring about only a slight amount of a die residue in the extrusion molding process. The term xe2x80x9cdie residuexe2x80x9d used herein means a substance which is different in color or physical properties from the starting material adhered to a die in the extrusion molding of a thermoplastic elastomer. This die residue includes a yellow viscous substance, black fine particles and the like, and is considered to be a deterioration product of the starting polymer. The mechanism of occurrence of the die residue has not been clarified.